Vol. V'lll. Xo. lOi. 



THE AGlilCULTUJtAL NKWS. 



315 



FUNGUS NOTES. 



FUNGUS DISEASES OP THE 

 SUGAR-CANE. 



The following notes are for the most part taken fioni 

 ]!ulletin Xo. C< of the Division of Pathology and Phy.-^iology 

 of the Experiment .Station of the Hawaiian Sngar I'lanter-s' 

 As.sociation, entitled Finn/uii J/a/arHis of the Sti^ar-cani-, by 

 Dr. X. A. Cobb. 



A neat method of disinfecting cane cuttings, applicable 

 to plantations of the size usual in the West Indies, is described 

 by the author as follows : A .series of wooden tanks two 

 and a half feet in every direction is set up and filled with 

 Bordeaux mixture. Stiff wire baskets are provided, into 

 which the canes are jiut, and the baskets are then lowered 

 into the wooden tanks. The baskets are made of copiier 

 wire, -|-inch to A-inch mesh wire, mounted on a stiff frame, 

 and are provided with two strong handles. The baskets 

 must be firm so that they will not bulge and cause difficulties 

 in their removal by rubbing against the side of the tank; 

 and the mesh must be small enough to prevent the cuttings 

 from projecting and causing the same difficulty. It is 

 jio.ssible that baskets, somewhat similar to those employed 

 for making fish i)ots, etc., but with a smaller mesh and 

 provided with strong handles, could be manufactured in flu- 

 West Indies, which would serve the imrpose equally wcl', and 

 thus a considerable amount of the initial expense might be 

 saved. Two men can work these liaskets, and the series of 

 tanks is of such a length that by the time the last has hsen 

 filled with the disinfectant and the cuttings, the first basket 

 of canes has been in the liquid for a sufficient time, and is 

 ready for removal. It is merely lifted out on to a cart and 

 taken to the field where it is to be used. The tank is then 

 refilled, and the second basket treated in the same way. By 

 this means no time is lost, and the cuttings usually arrive 

 with the fungicide sufliciently dried upon them. 



Attention is called by the author to the facts that no 

 diseased canes should ever bs used for cuttings, and that 

 great care should be taken not to shatter the ends when 

 cutting cane for planting. All cane that shows red or 

 brown discolouration of the fibres or pith at the cut ends 

 should be rejected for planting purposes, as disinfecting 

 a cane that is already diseased internally is only a waste of 

 time and money. Cuttings should never be allowed to 

 become so dry that the ends split before they are planted. 



There are at least five fungi causing root di-sease in 

 Hawaii : two species of Jfamsinliis, M. sarchari and 

 M. J/tiwaiiensis, two belonging to the FbaWoidene, Ilhi//,haJ/us 

 foralloidcs and Clnthrus trilohatm, and one whose mycelium, 

 only, is known. The spores of the Phalloids are disseminated 

 by strongly flying files, and their mycelia are capable of living 

 on .several other plants besides cane, especially Lantana in 

 the case of It/ii/jJiaZ/ux, so that these fungi are more difiicult 

 to eradicate than Marasi/iius, which, in the writer's opinion, 

 is only found in Hawaii on sugar-cane. 



On the other hand, there is a considerable probability 

 that one at least of the two or nK>re species of Jllarasniiiis 

 responsible for the root disease in the West Indies is cai>ablo 

 of living on host plants other than the sugar-cane, though 

 this point has not yet been established. (Aaricti/tural iVeirs 

 \o\. VII, p. 1.3.5.) 



In Hawaii, however. Dr. Cobb is of opinion that Marax- 

 'inius may be entirely starved out of any field by ceasing to 

 plant cane, and either allowing the soil to lie fallow or 

 planting a rotation crop. The time nece.ssary to ensure the 

 complete starvation of the fungus is that required for the 



complete decay of any dead <.r living portions of cane in the 

 soil. This takes from one to three years, according to the 

 amount of cultivation the land receives. Occasional plough- 

 ing and careful tillage, either in the presence or absence°of 

 a rotation cioi>, will encourage saphrophy tic fungi and bac- 

 teria, and hasten the breaking down of the dead cane, and 

 the consequent disappearance of J/arasim'us On the whole, 

 the planting of alternate crops seems preferable to letting 

 the land lie fallow; but, in view of recent observations in the 

 West Indies, it seems probable that these crops wdll have to 

 be cho.sen with considerable care, when the main object is the 

 elimination of Marastii.ius from the field. 



As Jfmismiiis has no special means of distribution of 

 its spores (see A<jricultural Xawx, Vol. VIII, \). 297), it .seems 

 probable that re-infection of a field once freed from the fungus 

 can only be brought about by the conveyance of infected 

 earth, trash, or cane cuttings from other field.s, on implements, 

 the labourers' feet, carts, etc. Thus, once a field has been 

 freed, it might be kept free by careful attention to cleanli- 

 ness, or, if the disease did return, a careful watch would 

 reveal the fact, and immediate applications of lime to the 

 infected area, together with trenching, would probably prevent 

 the disease from spreading to any extent. 



DISEASE OF GROUND NUTS IN 

 DOMINICA. 



A fungoid disease lias recoitly been found to cause con- 

 siderable damage to the leaves and stems of ground nuts in 

 Dominica. The disease attacked the Spanish variety first, and 

 then spread to a i)lot of the Carolina Running variety, which 

 was next to the original plot. A plot of Dixie Giant, on the 

 other side of the Spanish and another of Tennessee Red 

 which adjoined the Carolina Running were unaftected when 

 the information was received. 



The disease appears in the form of numerous, definite, 

 black circular spots, which are somewhat raised, on the 

 underside of the leaf, and which cause a corresiwnding slight 

 depre.ssion on the upper surface. On the black spots, .small 

 brown velvety pustules are formed, arranged in concentric 

 circles. These pustules occur mainly on the lower surface of 

 the leaf, more rarely on the upper ; they are possibly due to 

 a fungus known as ."yeptogloi'u m arachidix, which is mentioned 

 as similarly affecting ground nuts in the whole of the Eastern 

 Hemisphere. In addition to the black spots, smaller brown 

 spots, due to the Uredo condition of one of the rust fungi, 

 were also found, on the leaves only. This fungus has been 

 reported as attacking the leaves of ground nuts in Mont- 

 serrat. It does not appear to cause any serious damage in 

 Dominica. The attack is probably largely due to the dampness 

 of the season, the rainfall in Dominica having amounted to 

 over 35 inches since .lune 1 1 of this year. 



Attempts are being made to check these fungi by means 

 of Bordeaux mixture, but the results have not beeu reported; 

 this treatment should prove effective. 



It would also be advisable to burn, or bury with lime, 

 all diseased leaves and plants, and to avoid planting ground 

 nuts on the same land for at least a year, as infection may 

 be disseminated by spores on old leaves in the soil. The 

 Sejjtogliicuiii fungus spreads most rapidly after the plants 

 are a month old. 



The Mycologist of the Ceylon Department of Agri- 

 culture is of the opinion that infection of land previously 

 free from the Scptoijloeum disease may be prevented by 

 careful disinfection of the seed before planting ; the 

 method employed by him was to soak the pod in a 2 per 

 cent, solution of formalin for several hours. {Ceylon Ad- 

 ministration Report, 1905.) 



